Control device



Mamh 16, 1943. J, W N 2,314,240

CONTROL DEVICE Filed Dec.- 31, 1941 Inventor: Joseph \M Owens.

H is AttOffie gjg Patented Mar. 16, 1943 CONTROL DEVICE Joseph W. Owens, Schenectady, N. Y., assignor to General Electric Company,

New York a corporation of Application December 31, 1941, Serial No. 425,153 I 6 Claims. (01. 200-83) I My invention relates to control devices, more particularly to electric refrigerator motor control devices, and has for its object a simple and reliable control device provided with a single knob for adjusting the device for a desired refrigerator temperature and for adjusting the device for a defrosting cycle of relatively wide temperature range.

This invention is an improvement over the invention described and claimed in a copending application Serial No. 400,632, filed on July 1, 1941 by Edgar H. Ayers, assigned to the same assignee as this invention.

In carrying out my invention in one form I provide an adjustable stop for the switch arm in its open circuit position together with a projection on the knob for adjusting the bellows spring, which projection engages the stop when the knob is moved to a predetermined position thereby to move the stop farther out of the path of the switch arm. lThis provides for an increased opening movement of the switch arm whereby a high defrosting temperature in the evaporator is required to reclose the switch arm. I also provide a second projection on the knob for engaging the switch arm to hold the switch arm in its open circuit position when the knob is turned to another position.

For a more complete understanding of my invention, reference should be had to the accompany'ing drawing in which Fig. 1 is a plan viewof a control device embodying my invention; Fig. 2 is a sectional view along the lin 2-2 of Fig. 1 looking in the direction of' the arrows; Fig. 3 is a bottom view of the device with the knob removed; while Fig. 4 is a view of the inner operative end of the knob.

Referring to the drawing, in one form of my invention I provide over-center spring snap operating means for the switching means comprising a switch arm I. mounted on a pivot H and provided with a flexible arm I! carryingon its end a movable contact I3 which cooperates with a stationary electric contact It. This switch arm is by an operating arm l5 having a pivot I operated by a bellows temperature respondevice II. The over-center spring connecbetween these two arms I! and I5 comprises I! having its ends pivotally sethe ends of two laterally I! (only one of which is extending projections shown) which are spaced apart and secured'to the end of the operating arm IS. The cross or base portion of the link is connected by an over-center helical tension spring 22 with a projection 220 on the end of the switch arm l0 and extending laterally therefrom.- This projection 22a is positioned to move between the projections is upon relative movement between the two arms l0 and I5. Stops 24 and 25 made of electrically insulating material are provided on opposite sides of the link It adjacent its closed movable end for the purpose of limiting the movement of this end.

In the operation of this over-center snap mechanism, the determining factor is the relative positions of the pivot 20 and the pivot 23 forming the connection between the spring 22 and the projection 22a. When the pivot 20 is below the pivot 23, as viewed in Fig. 1, the spring applies a force holding the link l8 against the upper stop 2 ends. force to the arm in biasing it in a counterclockwise direction so as to hold the contact I! in engagement with the contact I4. If now the arm I5 is raised, as viewed in Fig. 1, until the pivot 20 is slightly above the pivot 23, then the spring applies a component of force tendin to move the link l8 clockwise about its pivot 20 into engagement with the lower stop 25. This, of course, changes the position of the end of the spring and thereby reverses its component applied to the arm Ill.v As seen in Fig. 1, the spring applies a force along a line passing through the pivot 23 and extending above the pivot I I. Soon after the link l8 begins to move downward the line of force of the spring moves below the pivot ll whereby a counterclockwise torque is applied to the arm I!) and the arm is therefore snapped in a counterclockwise direction to its open circuit position.

In accordance with my invention, I provide for an abnormally great movement of the arm it in the circuit opening direction whereby the pivot 23 is allowed to move to a-lower position, as seen in Fig. 1, and as a result. in order to move the contact arm ID to its closed circuit position, the arm l5 must be moved correspondingly lower. To effect this a higher bellows pressure and higher temperature are required with the result that the evaporator of the refrigerator to the temperature of which the bellows is responsive is allowed to reach a high defrosting temperature before the refrigerator motor is restarted.

In the form of my invention shown, I provide an extension 28 extending downwardly anc' iaterally from the switch arm ill, as viewed in Fig. 1.

On its end this extension 26 isprovided with a portion 26!; behind the bellows spring adjustin screw 21, parallel therewith. and projecting through an aperture 28 provided for it in the enclosing casing it for the mechanism into cooperative relation with a knob ill secured on the end of the adjustment screw 21.

As shown in Fig. 3, a stop ii is provided on the base of the casing for limiting the movement of the end 26a toward the right hand, i. e., in the opening direction. This stop, as shown, is the laterally bent end of a wire 32 lying in a recess 33 in the bottom of the electrically insulating casing 29. The other end of this wire is secured to the casing by means of the clamping screw 34. A bend 35 in the wire engages the wall of the recess 33 thereby to position the wire.

Also, the wire is provided with a laterally extending bent portion 36 extending downward, as seen in Fig. 1, which portion is in position to be engaged by a cam projection 31 on the inner end of the knob 30. Thus movement of the knob in a counterclockwise direction, looking at the bottom of -F'ig. 1, brings the curved portion 31a of the cam into engagement with the projection 36 whereby this projection is pushed out toward the right hand and the stop 31 carried by the wire likewise moved toward the right hand out of the path of the extension 26a to the position shown in dotted lines in Fig. 3. It will be understood that the wire 32 is made of spring material and bends to provide for this displacement of the stop 3|.

Also provided on the inner end of the knob is a projection 38 which is in position to engage the extension 26a and move it also toward the right hand by a still greater counterclockwise movement of the knob 30. Thus the extension 26a is relatively close to the adjustment screw 2! while the projection 38 is a greater distance away from the screw 21. Likewise, the projection 38 is the same distance from the center line of the knob as the extension 26a and the cam 31 is a greater distance away form the center line of the knob and moves outside of the extension 26a and does not engage it. Likewise, the projection 28 upon maximum clockwise rotation of the knob moves inside of the projection 36 and does not engage it.

Moreover, the cam 3'! is long enough in the direction of rotary movement of the handle so that it still engages the projection 38 when the knob is turned its maximum amount against the extension 26a. In other words, for the defrost setting, the knob is turned to a position in which the middle of the cam 81 engages the projection 36 so that the stop ii is moved to the dotted line position (Fig. 3) but the projection 38 is to the left of the extension No, as viewed in Fig. 3. and does not interfere with the extension. Thus the switch arm is free to move to its normal closed position. This position of the knob for the defrost setting will be indicated by a suitable mark (not shown) on the knob cooperating with a mark on the casing.

Not only must the bellows i! compress the spring 39 farther when th knob has been turned to this defrost setting which would require an increased bellows pressure, and temperature, but

the operating arm I! engages a spring pressedplunger 40 which is pressed upward by th spring ll normally until the flange 42 on the plunger engages the lateral end of a bracket 43. It will be understood that under normal operating conditions with the stop 3| in its normal position,'the bellows arm I! is not depressed far enough to engage the plunger II in order to move the con tact arm in to its closed circuit position. When the bellows arm engages the plunger 40, the spring ll still further loads it and increases the required bellows pressure and temperature to the desired high defrosting value.

It will be understood that the adjustment screw 21 is provided with a coarse thread having suflicient pitch to give the desired range of adjustment of the bellows spring ll in somewhat less than one complete revolution of the screw.

- The lower end of the spring 39 rests on a traveling nut 44 in threaded engagement with the screw. This nut is prevented from turning by means of a pair of prongs 45 (only one of which is shown) embracing a rib on the inner wall of the casing, which rib extends parallel with the screw. Moreover, the pitch of the screw threads is preferably in such direction that counterclockwise movement of the knob compresses the spring 39 so that when the defrost setting is made the spring is compressed.

A suitable connection terminal 46 is provided for the stationary contact ll, the two being connected together by a suitable screw or rivet.

Also, a connection screw 41 spaced and electrically insulated from the screw 4| is provided for the movable contact II. This terminal 41 is connected to a. rigid conductor 48 inside the casing which, in turn, is electrically connected by means of a flexible lead 48 to the contact arm ll. As previously stated, the bellows l1 preferably is responsive to the temperature on the evaporator of the refrigerator, the end ill of the closed tube connected with the bellows being suitably clamped on the evaporator so as to be responsive to the temperature of the evaporator. As shown,

this end 50 is provided in lieu of a bulb with a twisted portion formed by bending a portion on the end of the tube back on the tube and then twisting together the two lengths thus formed, as shown in the drawing.

A stop BI is provided on the knob on its periphery in position to engage a stop I! on the bottom of the casing thereby to limit the freedom of rotation of the knob to slightly less than one complete revolution, i. e., to one revolution less than the combined circumferential lengths of the stops.

Preferably, the projections 31 and II on the handle perform their control functions near or at the limits of counterclockwise rotation of the knob as determined by the stops II and I2. When the knob is turned to hold the switch arm II in its open circuit position, i. e., refrigerator of! position, the knob is turned its maximum amount in a counterclockwise direction looking at the bottom of Fig. 1 until the stop ll engages the stop 82. This brings the stop 88 into engagement with the projection 280- on the switch arm and moves the switch arm to its open circuit position or holds the switch arm in its open circuit position when it happens to be in that position.

A stop 53 on the arm iii engages with an abutment 54 on the casing to limit the downward movement of the arm II.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do. not wish to be limited thereto, since many modifications may be made and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A control device comprising a switch member, a temperature responsive operating member.-

aspring forming an operating connection be- 7 tween said members for biasing said switch memof said operating member to move said switch member to a closed circuit position, and a spring sponse to an increase in temperature, a stop member for limiting the open circuit position of said switch member to a predetermined normal position, a knob, a, projection'on said knob for moving said stop member to an abnormal posi tion upon rotation of said knob to a predetermined position thereby to provide for an increased opening movement of said switch member whereby an increased movement of said operating member is required to move said switch member to a closed circuit position, resilient means in the path of movement of said operating member in moving said switch member to a closed circuit position normally not engaged by said operating member when said switch member is in said predetermined normal open position but engaged by said operating member during its said increased movement thereby to increase the required pressure by said operating member for operation of said switch member to its closed circuit position, and a second projection on said knob for engaging said switch mem-q ber upon rotation of said knob to another pre determined position, thereby to hold said switch member in its open circuit position.

2. A control device comprising a switch momber, a temperature responsive operating member, a spring forming an operating connection between said members for biasing said switch member from an open to a closed circuit position upon movement of said operating member in response to an increase in temperature, a. stop member for limiting the open circuit position of said switch member to a predetermined normal position, a

second spring opposing movement of said operating member, a knob connected to vary the force applied by said second spring upon rotation of said knob, a projection on said knob for enga ing said stop member'thereby to move said stop member to an abnormal position upon rotation of said knob ina predetermined direction to a predetermined position thereby to provide for an increased opening movement of said switch member whereby an increased movement oi said operating member is required to move said switch member to a closed circuit position, resilient means in the path of movement of said operating member in moving said switch member to a closed circuit position normally not engaged by said operating member when said switch member is in said predetermined normal open position but engaged by said operating member during its said increased movement thereby to increase the re quired pressure by said'operating member for operation 01' said switch member to its closed circuit position, and a second projection on said pressed member positioned outside the normal,

range of movement of said operating member in moving said switch member from its predetermined normal open circuit position to its closed circuit position but engaged by said operating member during said increased movement for increasing the required pressure by said operating member for operation of said switch member to its closed circuit position, the temperature of the evaporator for such movement of said switch member to a closedcircuit position being increased to a temperature eifecting defrosting of the evaporator and said switch member being free to be moved between it's closed and open circuit positions by said temperature responsive means in' response to the-normal low evaporator temperature and said abnormal high defrostin temperature to efiect defrosting of the evaporator at said high temperature.

4. A control device comprising a switch member, a temperature responsive operating'member, a spring forming an operating connection between said members for causing said switch member to snap from an open to a closed circuit position upon movement of said operating memknob for engaging and moving said switch mem-' g ber to a predetermined position upon rotation of said knob to another predetermined position.

3. A control device for electrically operated reirigerators comprising a switch member, an operating member for said switch member, means responsive to the temperature of the evaporator of a refrigerator for operating said member, a snapping spring connection between said switch member and said operating member, a stop member for limiting the open circuit position or said switch member to a predetermined normal position, a rotatably mounted knob, a-projection on said knob for moving said stop member to an abnormal position upon rotation of said knob to provide for an increased opening movement of said switch member and anincreased movement perature's o! the evaporator or ber in response to an increase in temperature, a stop member for limiting the open circuit position of said switch member to a predetermined normal position, a spring opposing movement 0! said operating member in response to an increase in temperature, a knob connected to vary the force applied by said spring upon rotation of said knob, a cam projection on said knob for moving said stop member to an abnormal position upon rotation of said knob to a predetermined position of increased force applied by said spring to provide for an increased opening movement of said switch-member whereby an increased-movement of said operating member is required to move said switch member to a closed circuit position, a spring pressed member engaged by said operating member during said increased movement, and a second projection on said knob for engaging said switch member to hold it in said open circult position upon continued rotation of said knob past said predetermined position, said cam being arranged to hold said stop in said abnor- -mal position during said continued movement.

erating member for said switch member, means responsive to normal high and normal low tema refrigerator for operating said member between closed and open circuit positions, a snapping spring connection between said switch member and said operating member, a stop member for limiting the open circuit position 01' said switch member to a predetermined normal position, a rotatably mounted knob, a cam on said knob for moving said I I stop member to an abnormal position upon rotation of said knob to a predetermined position thereby to provide for an increased opening movement of said switch member whereby an increased movement of said operating member,

is required to move said switch member to a closed circuit position and the temperature of the evaporator for such movement of said switch member to a closed circuit position is increased to a high defrosting temperature eflectlnx defrosting ot the evaporator, resilient means in the path of movement of said operating member in moving said switch member'toja closed circuit.

position normally not engaged by said operating member when said switch member is in said predetermined normal open position but engaged by said operating member during its said increased movement thereby to increase the required pressure by said operating member for operation of said switch member to its closed circuit position, said switch member being tree to be moved between said closed and open circuit positions by said temperature responsive means in response to said high deirosting temperature and said normal low temperature to eil'ect defrosting oi' theevaporator at said high temperature, and a second projection on said knob for engaging said switch member upon rotation of said knob to another predetermined position thereby to hold said switch member in its open circuit position, said cam being arranged to hold said stop in said abnormal continued movement.

6'. A control device comprising a switch memher, a temperature responsive operating member, a spring forming an operating connection between said memberstor biasingsaid switch member from an open to a closed circuit position upon movement of said operating member in response to an increase in temperature, a second spring opposing movement of said operating member, means for varying the force 01' said second spring,

position during said a knob provided with a fixed pivot connected to operate said Iorce varying means, a spring latch having at least a portion lying in a plane perpendicular to the pivot of said knob, said portion being provided with a stop projection having a normal position near the pivot oi the knob and with an operating projection extending substantially parallel with the pivot of said knob but spaced farther from said pivot than said stop projection, an extension on said switch member engaging said stop projection when said switch member is in its open circuit position and extending substantially parallel with the pivot of said knob toward said knob, a projection on said knob extending parallel with the pivot 0! said knob for engaging said operating projection upon rotation 01- said knob in a predetermined direction thereby to move said stop projection to an abnormal position and provide for an increased opening movement of said switch member whereby an increased movement of said operating member is required to move said switch member to a closed circuit position. and a second projection on said knob nearer the pivot oi said knob than said first projection thereby to engage said extension upon continued movement of said knob in said predetermined direction and move said switch member to its open position.

JOSEPH W. OWENS. 

